Update `res` var in NPM docs example

[aziznatour]

Hello, the NPM README/docs has an invalid example code

https://www.npmjs.com/package/http-post#examples

http.post('http://localhost/postscript.php', { name: 'Sam', email: 'sam@emberlabs.org' }, function(res){
	response.setEncoding('utf8');
	res.on('data', function(chunk) {
		console.log(chunk);
	});
});

response.setEncoding('utf8'); should be res.setEncoding('utf8');